Sorry for leaving this idle so long.
Since posting this I have updated Ubuntu now to 19.04 and did a test of closing the program after a photo download. It seemed to close alright, but was a bit slow doing so. I have seen the original problem up until this recent system update.
I just got an error from pixls.us saying the upload file format wasn’t permitted (for the log files requested). I’ve added some log files via Launchpad although it only seems to permit one attachment per posting so I’ve made 2 posts with attachments.